Clean up function of CBC

[djs0109]

Describe the bug
The clear function for context broker has bug when only use client object as input

To Reproduce

    ...
    fiware_header = FiwareHeader(service=SERVICE, service_path=SERVICE_PATH)

    # Create a Context Broker Client
    cb_client = ContextBrokerClient(url=CB_URL, fiware_header=fiware_header)
    clear_context_broker(cb_client=cb_client)

Expected behavior

• Bug fix
• Implement test to ensure all the cleanup functions can accept both url+fiware_header and client object

[djs0109]

consider merge the implementation from #284 .

[github-actions]

Branch 331-Clean-up-function-of-CBC created!